Folding beam compass



E. A. MUTTER FOLDING BEAM COMPASS April 25, 1967 Filed May 13, 1966 INVENfbR.

' ERW/N A. MUTTER mdl A TTORNEV United States Patent O 3,315,361 FOLDING BEAM COMPASS Erwin A. Mutter, 313 N. Stiles St., Linden, NJ. 07036 Filed May 13, 1966, Ser. No. 549,929 1 Claim. (Cl. 33-27) This invention relates to a folding beam compass employed in drafting and similar applications. More specifically, it deals with a beam compass having a foldable arm locka-bly adjustable in any position, as well as other valuable features.

Beam compasses having fixed extendable arms have been described in the art. One example is the beam compass disclosed in copending application Ser. No. 459,171 filed on May 27, 1965, by Erwin A. Mutter, now Patent No. 3,263,334. One disadvantage of such devices is that the arcs and circles drawn thereby are limited due to the fixed pencil hole openings in the arm thereof. This has been overcome to some extent, by use of a Vernier screw adjustment, but such adjustment is slow and time-consuming.

According to the present invention, a beam compass is provided which has a hinged lockable arm that may be swung into any position over the work, while the main compass pivot remains fixed, whereby the are or circle centers may be varied easily and without endangering any change in the main pivot.

.The invention will be more readily understood by reference to the accompanying drawing in which a preferred embodiment is described, and in which the same numerals refer to similar parts in the various figures.

In the drawing:

FIGURE 1 depicts a top or plan view of a beam compass of the present invention, in open position.

FIGURE 2 illustrates a similar view of the same compass in closed position.

FIGURE 3 presents a front side elevational view of the unit shown in FIGURE 2.

FIGURE 4 shows a cross-sectional side view of the main pivot portion taken along the plane of lines 4-4 in FIGURE 1.

FIGURE 5 depicts a top view of the main pivot portion taken along the plane of lines 5-5 in FIGURE 3.

Referring again to the drawing, numeral represents the main compass pivot around which the arcs or circles are to be drawn. This pivot is desirably made of transparent plastic and has a widened fiat base portion 11 which is to be disposed over the surface on which the arc or circle is to be drawn. A cross-hair 12 is desirably drawn on the base to more readily spot the center of the are or circle to be drawn. The pivot also has a fiat 13 or rounded 13 upper portion to be held by finger pressure. The center portion of pivot 10 has a narrowed circular neck 14 around which arm 15 is designed to rotate.

Short arm 15, also desirably made of transparent plastic, has one end 16 provided with a circular opening 17 which fits tightly around pivot neck 14. The other end 18 of arm 15 is widened to accommodate a semi-circular slot 19 in which rides locking screw 20.

Longer arm 21, likewise desirably made of transparent plastic, has one end pivoted to end 18 of the short arm 15, at screw 22, around which it is designed to rotate. Screw 20, having its bottom 23 anchored in arm end 18, projects through slot 19 and is used to lock longer arm 21 in any position onto shorter arm 15. Arm 21 has an arcuately shaped portion 21 designed to be disposed around pivot 10 so as to maintain the remaining portion of arm 21 in parallel alignment with arm 15, when in closed position. Also, arm 21 is provided with pencil point holes 24, through which pencil points may be in- 3,315,361 Patented Apr. 25, 1967 serted as both arms (in locked position) are rotated around pivot 10 to draw the desired are or circle. Pencil point holes 24' may also be provided on short arm 15, if desired. Arm 21 may be provided with an extension 21", if arcs or circles, beyond the capacity of arm 21, are desired.

When in use, cross-hairs 12 are centered at the desired are or circle center, and the nearest pencil hole, say hole 24", in arm 21 is selected. Thereafter, screw 20 is loosened, and arm 21 is moved around pivot 22 until the desired arc or circle diameter is reached, whereupon screw 20 is tightened and a pencil point is inserted in hole 24", and the arc or circle is drawn while pivot top 13 is pressed down with the fingers of one hand to insure that the main pivot is not moved. It will be noted that arm 21 may be in the closed position, as in FIGURE 2, or in the completely open position, shown in broken lines as 21a in FIGURE 1, or in any intermediate position, so that a wide variety of diameter selections are readily selectable.

I claim:

A beam compass, comprising:

a main centering pivot made of transparent material and having a wide fiat bottom and a round neck, and carrying cross-hairs visible from the top of said pivot, for use in centering,

a short narrow flat arm having one end mounted around said pivot neck in close-fitting relation and designed for rotation of said arm completely therearound, and having pivot means on its opposite end,

a longer fiat narrow arm having a width equal to that of the flat bottom of the pivot and having one end pivoted at said pivot means with the top surface of the longer arm contacting the bottom surface of the short arm and arranged to be rotated around said means, and having locking means for locking it to said shorter arm in any rotational position, said longer arm having an arcuate cutout portion of radius at least as great as the width of said longer arm portion and of a radius for encompassing substantially all of the flat bottom of the pivot, said arcuate portion being designed to fit around said fiat bottom of the main pivot when said compass is in folded position, whereby both arms are disposable in overlying parallel condition, and with the bottom surface of said flat bottom of the pivot and the bottom surface of said longer arm being in the same plane, and

pencil holes disposed in said longer arm for insertion therein of a pencil point for drawing an are or circle as said locked arms are rotated around said main pivot.

References Cited by the Examiner UNITED STATES PATENTS 732,827 7/ 1903 Chambers 33-105 774,365 11/1904 Phenix 33-105 X 883,112 3/1908 Jacob 33-105 1,878,119 9/1932 Dowd 33-105 2,542,537 2/1951 Klemm 33-27 2,667,697 2/ 1954 McGrath 33-105 2,850,804 9/1958 Massari 33-26 2,899,749 8/ 1959 McWhirter et al. 33-75 3,065,546 11/ 1962 Brocklander 33-75 FOREIGN PATENTS 677,094 8/ 1952 Great Britain. 381,592 7/ 1940 Italy.

LEONARD FORMAN, Primary Examiner. H. HAROIAN, Assistant Examiner. 

